Answer:
A. A southern strip of land in Arizona and New Mexico.
Step-by-step explanation:
The Gadsden Purchase was a contractual agreement between Mexico and the United States of America with respect to the purchase of a portion of Mexico.
In 1853, the President of the United States of America, Franklin Pierce instructed the U.S Minister to Mexico, James Gadsden to buy the northern territory of Mexico. The government intended to use that portion of Mexico as a southern route for the construction of the transcontinental railroad.
The transaction was finalized in 1854 as the United States of America agreed to pay $10 million for a 29,670 square mile (76,800 kilometer square) portion of Mexico, which is today referred to as Southern Arizona and Southwestern New Mexico.
Hence, in the Gadsden Purchase of 1853, the United States of America purchased a southern strip of land in Arizona and New Mexico, after signing a contractual agreement with Mexico on the 30th of December, 1853.